I. Field of the Invention
This invention relates to a fuel injection system and fuel flow control devices in general. This invention relates more specifically to devices for mechanically controlling fuel flow to injectors.
II. Description of the Prior Art
Various types and arrangements of fuel control devices for fuel injection engines have been shown in the prior art. Most of these devices are more complicated and more expensive to manufacture than the present invention. In many of the devices, a separate accelerator pump is needed to increase the fuel supply indirectly by increasing the rpm of the accelerator pump according to the accelerator pedal. This pump represents an added expense and suffers from many of the same problems of the devices discussed below.
Recently, various types of electrical controls have been provided for regulating the flow of fuel according to various factors such as engine rpm, manifold pressure, and other engine variables. These electrical controls represent an additional expense and suffer from various defects discussed below.
Fuel injectors of various designs have been provided for use in engines, especially racing engines. These various designs have included the air gap type such as is disclosed in Hilborn, U.S. Pat. No. 3,473,523. These injectors rely upon the air pressure in the manifold for operation of the injector to draw fuel into the combustion chambers. Other types have been used, especially in racing engines, wherein the supply of fuel to the combustion chamber through the injector is dependent upon either the manifold pressure, the fuel line pressure to the injector, or both. Many of these designs have included a spring-loaded valve. Various problems have resulted from all of these types of fuel injectors with the conventional fuel supply systems known in the prior art.
One particular problem is the waste of fuel after the engine has been shut off. The injectors tend to slowly drip fuel into the combustion chambers after the engine has been shut off since a certain amount of pressure remains in the fuel line supplying fuel to the injectors. The dripping fuel sometimes causes flooding of the engine when the engine is started again. In any case, fuel drip constitutes a waste of fuel which is to be avoided.
All of the fuel supply systems of the prior art, although giving good controlled progressive increase of fuel input to the combustion chambers, provide little or no capability for controlled progressive decrease in fuel input to the engine for the operator of the vehicle or other device using the engine. This lack of control for reducing the fuel input always results in a waste of fuel and presents another factor which the operator of the engine must control upon deceleration of the engine. This has been especially critical in racing engines where it is desired to immediately reduce the fuel supply to an engine while using a minimum of braking for the vehicle. The conventional fuel supply system for a fuel-injected engine cuts off only the air to the engine when the accelerator pedal is released. The fuel, however, is still under pressure and at least momentarily supplies excess fuel to the engine thereby requiring the operator of a vehicle using a fuel-injected engine to use other measures to control the deceleration of the engine and vehicle. Furthermore, in endurance races, a waste of fuel may require an additional refueling stop which in turn wastes precious time.
Since the accelerator pedal of vehicles using a fuel-injected engine is commonly connected to the throttle valves in the air stacks above the combustion cylinders by a mechanical throttle linkage, the air supply to an engine can be immediately cut off. However, since the fuel supply is not accordingly reduced, a rich mixture results. This results in a waste of fuel, poor combustion, and a high output of hydro-carbons in the exhaust, resulting in increased pollution.
Many other problems have been found with the devices of the prior art, especially problems related to deceleration of the engine and reduction of fuel supply upon deceleration. For example, the low pressure remaining in the manifold above the combustion cylinders, even after the accelerator pedal has been released, causes additional fuel to be sucked into the fuel injector (especially the air-gap type) thereby causing the resulting problems discussed above.